A taxonomic guide to the fanworms (Sabellidae, Annelida) of Lizard Island, Great Barrier Reef, Australia, including new species and new records
Author
Capa, María
Author
Murray, Anna
text
Zootaxa
2015
4019
1
98
167
journal article
10.11646/zootaxa.4019.1.8
9f11b13f-1fcc-4618-a8e2-e2a56340c6a1
1175-5326
240803
8C14F828-F8FB-4783-928B-399B33B4246D
Megalomma
sp. cf.
M. kaikourense
Knight-Jones, 1997
(
Fig. 13A–D
)
Megalomma kaikourense
Knight-Jones, 1997
: 320
–321, fig. 5.
Material examined.
AM W.45166, MI
QLD
2444 (3).
Description of material examined.
Specimens measuring up to
26 mm
long and
3 mm
wide, with eight thoracic and numerous abdominal chaetigers. Specimens not studied alive. Preserved material pale, some with radioles slightly pigmented with brown or orange (
Fig. 13B–D
). Radiolar eyes black (
Fig. 13B
). Body is pale cream, without spots, except for red pygidial eyepots. Radiolar crown with semicircular lobes. Dorsal and ventral flanges absent. Basal membrane and radiolar flanges absent. Six to eight vacuolated cells supporting radioles in cross section, basally. Dorsalmost pair of radioles longer than the rest, each with a large subdistal compound eye almost surrounding the whole radiole (
Fig. 13B
). Dorsal lips with medium radiolar appendages, dorsal pinnular appendages absent. Caruncle absent. Ventral lips and parallel lamellae present, ventral sacs inside radiolar lobes. Posterior peristomial ring with margins separated by a wide gap, not fused to faecal groove, forming very low dorsal pockets only in some specimens (
Fig. 13C
versus
13D); large triangular ventral lappets separated by a midventral incision (
Fig. 13B
). Glandular ridge absent on anterior chaetigers. Thoracic ventral shields separated from adjacent neuropodial tori by a gap (
Fig. 13B
). First ventral shield with M-shaped anterior margin. Interramal eyespots absent. Collar chaetae elongate narrowly-hooded in two oblique rows. Following thoracic chaetigers with conical notopodia, with superior elongate narrowly-hooded and inferior broadly-hooded notochaetae (
type
B). Thoracic neuropodial uncini avicular, with several rows of small similar-sized teeth above main fang, well developed breast and medium-sized handle. Companion chaetae with asymmetrical hood, and dentate appearance on proximal half of hood. Abdominal neuropodia as low elevations with elongate, broadly-hooded chaetae arranged in rows. Notopodial abdominal uncini similar to thoracic uncini but with shorte handle. Pygidium with a low rim around ventral anus; two red eyespots on each side. Tube mucous with sediment and medium-sized calcareous particles such as shell and coral fragments and foraminiferans.
Remarks.
These specimens are characterised by the presence of single radiolar eyes on the dorsalmost pair of radioles, collar dorsal margins not fused to faecal groove but possessing incipient lateral pockets on some specimens, lack of a caruncle, thoracic ventral shields separated from neuropodial tori and broadly-hooded inferior thoracic chaetae (
type
B). With these features, the specimens belong to "Group 2A" (
sensu
Knight-Jones 1997
) and "Group 2A2" (
sensu
Capa & Murray 2009
), groups recovered as paraphyletic from cladistic analyses of the genus performed so far (
Capa & Murray 2009
;
Tovar-Hernández & Carrera-Parra 2011
). The Lizard
Island
specimens share the same pigmentation pattern as the
type
material (
Knight-Jones 1997
). The specimens described herein differ from those from
New Zealand
by their size, the ones from Lizard
Island
being more than twice the length of those in the original description. Other minor differences may be a consequence of size, such as the length of dorsal lappets. The specimens examined herein possess inferior thoracic chaetae slightly more elongated than those drawn by
Knight-Jones (1997)
. It would be ideal to compare further material of similar size to confirm the presence of this species in Australian waters.
Habitat.
Sand and seagrass,
24 m
depth.
Type
locality.
Kaikoura,
New Zealand
.
Distribution.
New Zealand
,
Australia
(Queensland: Lizard
Island
).